Networks provide for transmission of information from a source to a destination over a particular route. The information is transmitted along the route through routers. The information is transmitted throughout the network in accordance with a particular protocol and routers in the network may support any of a number of protocols. Typically, each router has knowledge of various routes available in the network and this knowledge is stored in a route database or route table. Thus, the router may store multiple routes, which are available using multiple protocols.
The Internet has become a particularly important network for transmission and distribution of data (text, code, image, video, audio, or mixed) and software. Users connect to the backbone of the Internet with broadly divergent levels of performance, ranging from 14.4 Kb/s to more than 45 Mb/s. Transmission Control Protocol/Internet Protocol (TCP/IP) has become a widely implemented standard communication protocol in Internet and Intranet technology, enabling broad heterogeneity between clients, servers, and the communications systems coupling them. Internet Protocol (IP) is the network layer protocol and Transmission Control Protocol (TCP) is the transport layer protocol. At the network level, IP provides a “datagram” delivery service. By contrast, TCP builds a transport level service over the datagram service to provide guaranteed, sequential delivery of a byte stream between two IP hosts.
Often, the hosts in a network operate both as a router and a host. Such hosts are able to forward packets that are destined for other hosts within the network. When a router/host server receives a packet over the network, it must spend considerable resources verifying whether the packet should terminate on the resident host or be sent forward to another addressed host. Processing resources and corresponding cost to make this verification substantially increases as the number of IP addresses belonging to the host increases. This results because the destination address in the packet must be compared with all the IP addresses associated with the host to confirm that the packet terminates on that host, or must be passed to the routing functionality of the host to calculate and execute a route for the packet to the ultimate destined host down the route. In large, busy systems with multiple IP addresses designated for the various hosts, there can be a considerable amount of processing resources expended on checking that a received packet contains a destination address of the host server.